1. Technical Field
The present disclosure is directed to nitrated and amine-reacted derivatives of asphaltenes. The disclosure includes a process for reacting a nitrating agent with an asphaltene to form a nitrated asphaltene. The disclosure also includes a process for reacting an amine with an asphaltene to form an alkylated or arylated asphaltene.
2. Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Petroleum heavy residue conversion processes are increasingly important in the petrochemical industry due to market and economic factors. In the future, it is projected that the petroleum industry will increase its reliance on much heavier crude oil supplies. The increased heavy crude oil feedstock supply availability will further result in increasing yields of low value refinery residues, such as residual fuel oil and coke. Depending on the nature of crude oil, these refinery residues can present up to about 60% of the original crude oil. The residue of heavy crude oils can be upgraded [Lepage, J. F.; Chatila, S. G.; Davidson, M. In Residue and Heavy Oil Processing; Editions Technip: Paris, 1992. Incorporated herein by reference in its entirety].
One of the challenges the petroleum industry faces with upgrading residues is how to handle a molecular substance known as an asphaltene. Asphaltenes are components of crude oil that are present in all of the petroleum processing phases. Although found in insignificant quantities, they are nonetheless one of the most notable compounds present in petroleum due to their precipitation and flocculation properties. Asphaltenes can also increase the viscosity of oil, which can in turn reduce, or even halt, its flow. Furthermore, asphaltenes are known to be coke precursors in acid catalysis and can act as catalyst inhibitors by catalyst deactivation and catalyst poisoning. As such, asphaltenes pose a serious problem to a variety of processes in the petroleum industry.
Generally, there are two main approaches in dealing with asphaltenes during the oil processing phases. Foremost, it can be deemed advantageous to maintain asphaltenes in a stable suspension in a crude oil liquid until well into the petroleum refining process. The ability to keep asphaltenes stable in the liquid results in higher production yields, and furthermore, a decrease or elimination of maintenance problems to industry equipment. This may be accomplished by the addition of a chemical group to the polycyclic core of an asphaltene, thus creating a functionalized asphaltene, in order to increase its solubility. Alternatively, the ability of asphaltenes to flocculate can be used to the industry's advantage, wherein an increased precipitation of asphaltenes, and their subsequent removal, will result in a less viscous petroleum feed stream. This may be accomplished by the addition of chemical groups to the polycyclic core of an asphaltene, thus creating a functionalized asphaltene, in order to decrease its solubility. Therefore, the reactivity behavior of asphaltenes is vital towards understanding the functional properties of asphaltenes to form aggregates, micelles, and coke in a variety of refining and upgrading processes of the petroleum industry.
On the molecular level, asphaltenes are composed of various chemical species. Asphaltenes have a low hydrogen to carbon (H/C) ratio, and are believed to possess several long paraffinic side chains as opposed to many shorter paraffinic side chains or naphthenic groups. Subsequently, they are known to be polar and insoluble in a paraffinic solvent. Furthermore, asphaltenes cannot crystallize and cannot be separated individually. The condensed structural units of asphaltenes bear alicyclic sites substituted and connected to aliphatic chains, with or without heteroatoms. Asphaltenes also include a heterogeneous mixture of highly polydispersed molecules, in terms of size and chemical composition, with a high content of heteroatoms (S, N, O) and metals (Ni and V) [Hasan, M.; Siddiqui, M. N. and Arab, M.; Oil and Gas Journal, 1988a, February 8, 38-40. Hasan, M.; Siddiqui, M. N. and Arab, M.; Fuel, August 1988b, Vol. 67, No. 8, 1131-1134. Incorporated herein by reference in their entirety].
Asphaltenes, depending on the source of crude oil, contain a variety of polycyclic aromatic hydrocarbons at their core. Several hundred polycyclic aromatic hydrocarbons have been identified in petroleum substances, such as asphalt. Also known as polyaromatic hydrocarbons, these organic compounds are composed of multiple aromatic rings in which the electrons are delocalized. Although poly signifies ‘many’, there is precedence in the nomenclature to refer to two-ring cases as biphenyl and naphthalene, while anthracene and phenanthrene are examples of three-ringed structures.
For Saudi crude oil, the asphaltene content characterized by condensed aromatic systems carrying alkyl, cycloalkyl and heteroatom constituents, has an average layer distance between aromatic sheets that measures approximately 3.6 Å. The average interchain layer distance is between 4.4 and 4.5 Å, and the average stack height of the aromatic sheets perpendicular to that plane of the sheets ranges between 22.7 and 24.7 Å. X-ray diffraction studies of the four Saudi crude oil asphaltenes support the concept of condensed aromatic sheets having a tendency to stack, bearing naphthenic and alkyl systems on their periphery [Shirokoff, John W., Siddiqui, Mohammad N., Ali, Mohammad F., Characterization of the Structure of Saudi Crude Asphaltenes by X-ray Diffraction, Energy & Fuels 1997, 11, 561-565 Incorporated herein by reference in its entirety].
Arab Berri asphaltene is found to possess the highest estimate of aromaticity followed by Arab Light and Arab Heavy, whereas Arab Medium is considered the lowest in aromaticity. Sulfur content decreases from Arab Heavy to Arab Medium to Arab Light and Arab Berri having equivalent amounts. Oxygen content increases from Arab Heavy to Arab Light to Arab Medium to Arab Berri. [Shirokoff, John W., Siddiqui, Mohammad N., Ali, Mohammad F., Characterization of the Structure of Saudi Crude Asphaltenes by X-ray Diffraction, Energy & Fuels 1997, 11, 561-565 Incorporated herein by reference in its entirety].
Bridgehead carbons, which serve to connect different rings within the same molecule, vary in comparison of the four Saudi crude asphaltenes. However, this parameter can be used to indicate the extent of compactness and ring condensation. [Shirokoff, John W., Siddiqui, Mohammad N., Ali, Mohammad F., Characterization of the Structure of Saudi Crude Asphaltenes by X-ray Diffraction, Energy & Fuels 1997, 11, 561-565 Incorporated herein by reference in its entirety].
As the petroleum industry looks for ways to increase yield from heavy crude oil fractions, attention has turned to studies involving the chemical reactivity of asphaltenes. For example, several studies have reported on the reductive and non-reductive alkylation of asphaltenes using different type of reagents. [Speight, J. G and R. J. Pancirov, R. J.; Preprints, Am. Chem. Soc., Div. Petrol. Chem. 28 (1983), p. 1319; Ali, M. F., Siddiqui, M. N. and Al-Hajji A. A., Petroleum Science & Technology, 2004, 22(5 & 6), p. 655; Cagniant, D.; Nosyrev, I.; Cebolla, V.; Vela, J.; Membrado, L. and Gruber, R.; Fuel, 2001, 80(1), 107. Incorporated herein by reference in their entirety].
Acevedo et al. have carried out the synthesis and isolation of octylated asphaltenes for the determination of more realistic molecular weight distributions of asphaltenes [Acevedo, S.; Escobar, G.; Ranaudo, M. A. and Rizzo, A.; Fuel, 1998, 77(8), 853 Incorporated herein by reference in its entirety]. Friedel-Crafts alkylation and potassium permanganate oxidation of Arab heavy and Arab medium asphaltenes have also been carried out to understand the chemical reactivity of asphaltenes. [Siddiqui, M. N. Fuel, 2003, 82(11), p. 1323 Incorporated herein by reference in its entirety]. The hydrogen bonding capacities of four Saudi Arabian crude-oil-derived asphaltenes against the phenol and piperidine solutions of various concentrations in carbon tetrachloride has also been explored. [Siddiqui, M. N., Petroleum Science & Technology, 2003, 21(9-10), p. 1601. Incorporated herein by reference in its entirety]. The chlorination reaction of asphaltenes has been disclosed as well. [Siddiqui Prepr. Pap.-Am Chem. Soc., Div. Fuel Chem 2009, 54(1), 14 Incorporated herein by reference in its entirety].
Therefore, in order to study the reactivity behavior, an asphaltene may be functionalized by the addition of a chemical group to its polycyclic core, or to a paraffinic side chain.